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# Rewinding a power transformer 1000KVA/11KVby 3KV 60HZ

## Rewinding a power transformer 1000KVA/11KVby 3KV 60HZ

(OP)
Dear all , I have three 3 Phase 1000KVA/11KV-3KV 60HZ transformers but I have a pump motor of 3 Phase 380V @50HZ I want to use these three transformer.
How could I rewind to get 1000KVA(less) 11KV-380V(400V)?

### RE: Rewinding a power transformer 1000KVA/11KVby 3KV 60HZ

Congrats on posting the 500000th topic on eng-tips. A true landmark

Huub
- You never get what you expect, you only get what you inspect.

### RE: Rewinding a power transformer 1000KVA/11KVby 3KV 60HZ

Jemal Dewit: Use your favorite search engine to figure out how transformers work. First basic rule: the turns ratio is the number of turns on the primary side winding divided by the number of turns on the secondary side winding. This is the same ratio as primary volt to secondary volt. Second basic rule: the power on both primary and secondary side is equal (e.g. volt * amp on primary = volt * amp on secondary). This means that if turns ratio does not equal unity, there will be more current (and less voltage) on one side than on the other. This ultimately affects the cross-section of the conductor used.

So - the original transformer was rated 1000 kVA at 11 KV, which means the primary current would be 90.9 A. For the original design with a 3 kV secondary, the output (secondary) current would be (11/3)*(90.9)= 333.3 A (ideally). In practice there are some losses.

Now figure out where you need to be for a 380 V output.

Converting energy to motion for more than half a century

### RE: Rewinding a power transformer 1000KVA/11KVby 3KV 60HZ

I’m pretty sure that the right transformer, new, will be less expensive and less hassle than a rewind.

I’ll see your silver lining and raise you two black clouds. - Protection Operations

### RE: Rewinding a power transformer 1000KVA/11KVby 3KV 60HZ

It's not a DIY project. A good rewind company can do the 380 V secondary for you. Do the cost comparison of new trafo vs rewind.

Muthu
www.edison.co.in

### RE: Rewinding a power transformer 1000KVA/11KVby 3KV 60HZ

#### Quote:

How could I rewind to get 1000KVA(less) 11KV-380V(400V)?

There is no way for someone on a site called ENG-TIPS, with the emphasis on it being a tips site, to detail how to do this. Taking them to a professional shop and asking there is the best advice I can give you.

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